Heretofore, only FM radio simulcasts could be substituted for a normal television audio program; a viewer has not previously had the option of substituting an AM radio simulcast for a television audio program. Television audio engineers have traditionally seen radio simulcasts as merely stereo versions of the original television audio broadcast, and have either provided no simulcast capability or the ability to substitute FM radio simulcasts for the television audio program. The similarities between FM radio circuitry and television audio circuitry, which permit FM radio signals to be amplified through pre-existing television audio circuits, have reinforced this mindset. A number of inventions which allow an FM radio simulcast to be substituted for a normal television audio program exist in the prior art; however, none of these designs will accommodate AM radio simulcasts. By ignoring AM radio, these teachings exclude nearly all radio simulcasts, since the vast majority of all radio simulcasts are found on AM radio.
Portable units with both televisions and AM/FM radios have been produced, but the radio of these combination units has always been separate from the television of the unit; no provision to substitute radio sound for television audio has been provided. The radio and television of these combination units have been perceived as separate entities which happen to share a common housing.
It is well known in the prior art that television audio circuits can be used to amplify FM radio signals; indeed, Middleton teaches that television audio circuitry is quite similar to the circuitry of an FM radio. The prior art has made heavy use of this similarity. Wignot et al., U.S. Pat. No. 5,142,370 (1992); Uee et al., U.S. Pat. No. 4,779,129 (1988); Ogita, U.S. Pat. No. 4,272,788 (1981); and foreign patents Gorenje, DT 2831-014 (1980); Hitachi, 53-17017 (1978); Suzuki, 57-45712(A) (1982); and Saitou, 57-155885(A) (1982) all use television audio circuitry to amplify the radio signal. Wignot carries this circuit-sharing to its logical extreme, disclosing a way to make a television audio circuit function efficiently as an FM radio receiver.
Every instance of applicable prior art known to the applicant has either ignored the potential synergy between radio simulcasts and television sets, or else limited itself solely to FM radio simulcasts by routing the radio signal through television circuitry to be amplified. Television audio circuits cannot be shared with an AM radio; the intermediate frequencies of the two signals are too dissimilar. Besides excluding AM radio simulcasts, the prior art has the additional disadvantage of depending on a particular television broadcast format. It is unlikely that Saitou's device will work in conjunction with an HDTV television set: Saitou, along with the entire body of applicable prior art, relies on a fortuitous similarity between television audio circuitry and FM radio that has little chance of surviving the transition from analog to digital television.
Kozokai et al., U.S. Pat. No. 4,527,204 (1985) discloses a remote control device which facilitates the synergy between a video cassette recorder and a television set. Kozokai's remote control device cannot be compared with the remote control device of this invention. Kozokai's remote control device merely simplifies the interactions of two already interdependent video media, rather than establishing new interactions between two dissimilar and non-interdependent media. Kozokai's remote control device automates the steps necessary to display a VCR signal through a television set; it performs only mandatory actions. In contrast, a switch on a remote control device which causes radio sound to be substituted for television audio creates an interaction between two different media; a new relationship between the two media. This switch is not essential to the operation of a normal television. It is only useful when a receiver capable of decoding AM radio transmissions is incorporated into a television set, at which time it provides the new and unexpected result of allowing the viewer to choose between the normal television audio program and a radio simulcast at the touch of a button. This switch is neither obvious nor cost-effective if only FM radio simulcasts are considered. Because FM simulcasts differ from the original television audio program by being in stereo, and most television sets provide marginal stereo separation, there is no reason to provide such a switch for a television with FM-only simulcast capability. Even if the average television set had widely-separated speakers and excellent stereo separation, the scarcity of FM radio simulcasts would prevent such a switch from being cost-effective. The prior art recognizes this and provides circuits which automatically compare the strength of the FM simulcast signal against the strength of the television audio signal, automatically selecting the stronger of the two signals. The viewer is not burdened with a choice between television audio and FM simulcast sound, since the two are essentially identical.
Iwamatsu, U.S. Pat. No. 5,046,107 (1991) discloses a device which adjusts volume such that when the user switches among various audio sources, the volume remains constant. He describes a memory which stores preset volume levels and associates each preset volume level with a particular device. Like Kozokai, this device refines pre-existing relationships, rather than creating new attributes. In contrast, a memory which can associate a radio frequency with a given television channel and make this radio frequency available whenever the television is tuned to the channel creates a new attribute for the television channel. It creates a new relationship between the television channel and the radio frequency, with the new and unexpected result that the viewer has a choice between the standard television audio program and one or more radio simulcasts which describe the same event, but which differ in content among themselves and the original television audio broadcast.
The need of the non-English-speaking person to watch a television picture while listening to a simulcast in his or her native tongue has not heretofore been fully addressed. Second-language simulcasts are to be found on AM, not on FM radio. Television broadcasters have attempted to accommodate non-English-speaking persons by offering a Secondary Audio Program (SAP), but not all languages are covered; nor is SAP offered for every program; nor is SAP available on every broadcast channel. Radio simulcasts in a number of languages exist today; the prior art has ignored them by designing televisions which are either confined to receiving FM radio broadcasts or which cannot receive radio broadcasts at all. The present invention allows AM foreign-language simulcasts to be easily accessed, without impairing the viewer's ability to receive a television SAP audio broadcast.
Many sports fans would prefer to watch sports on television while listening to the play-by-play commentary from their local radio announcer, but desire the option to hear the normal television audio program when statistics are displayed or during interviews or replays. Again, these sports simulcasts are found on the AM radio band, not on FM radio. The present invention gives these sports fans the "best of both worlds"--they can listen to the radio announcer for the play-by-plays; switch to the television announcer for the replays, statistics, and interviews; and switch back to the radio announcer when play resumes.
The need of a viewer of alternate television formats, such as HDTV and cable, to access AM simulcasts has not heretofore been addressed. By keeping the interdependency between the host television and the AM radio to a minimum, the present invention will work with a wide variety of television sets. All that is required is a television which eventually separates the Audio signal from the Video signal and sends this Audio signal to the speaker system to be reproduced.